Teletypewriter system



March 29, 1938. l J. F. BEATTIE ET AL 2,112,234

' TELETYPEWRITER SYSTEM Filed Sept. 9, 1956 2 Sheecs-Sl'leei'l lJEBEATT/E NVENORS' um. RorcRoFr ATTORNEY J. F. BEATTIE ET A1. 2,112,234

March 2.9, 1938.

TELETYPEWRITER SYSTEM Filed Sept. 9, 1956 2 Sheets-Sheet 2 mmf.

/Nl/E/voRs: J- E BEATT/E WRROYCROFT H/'roRA/Ey Patented Mar. 29, lees,2,l2,234

amro STATI-:s PATENT oFFlCE TELETYPEWRITER, SYSTEM James F. Beattie,Norwood, N. J., and Walter R.

Roycrcft, zone Park, N. Y., assignors to Western Electric Company,Incorporated, New York, N. Y., a corporation of New York ApplicationSeptember 9, 1936, Serial No. 99,940

13 Claims. (Cl. 178--23) This invention relates to teletypewriter sysbeoperated by the pull bars. This pivoted plate tems and, moreparticularly, to systems which has an effective position and anineffective posiinclude a teletypewriter having contacts for pertion.Biasing means normally tilt the DVOted y, forming various functions.plate in its ineffective position so that the con,-

It is an object of this invention to mount contacts are elevated beyondthe reach of the pull tacts, for performing various functions, in atelebars. Control means are provided fOr tilting the. typewriter to beoperated by the teletypewriter pivoted plate into its effective positionfor lowmechanism in response to the transmission and ering the contactsinto the reach of the pull bars.

Y reception ci any or all upper case characters The plate is locked inits effective position by H lo without hindering the printing functionsof these means provided for that DUYDOSe- A feW f the lo" characters.contact assemblies are mounted in other places It is also an object ofthis invention to open inthe teletypeWliter and are designedt0 be 0pe1`-and close, by means of a central teletypewriter, ated by certainmechanisms in the teletypewriter.

telegraph lines leading from a teletypewriter These and other featuresof the invention will y l oiiice to other teletypewriter stations. nowbe described in detail` with reference to the 15 It is a further objectof this invention to prodrawings in Wheh vide a central teletypewriteroffice with an im- Fig. 1 represents a teletYDeWIteI Central Ofleeproved switching device for switching various and shows a schematicdiagram in perspective of circuits. a teletypewriter having its platenassembly in It is an additional object of this invention to the lowercase position and DIOVided With Special 276'y enable a subscriber at ateletypewriter station to contacts and circuit connections leading t0the connect his teletypewriter through a teletypeswitching relays;writer central cnice to another teletypewriter Fig. 2 shows theswitching relays at the central station without the assistance of anoperator at olee and the other teletypewriter stations to the centraloffice thereby effecting a saving in which the teletypewriter centraloflice shown in operating time. Fig. 1 is connected;

It is a further object of the invention to @name Fie. 3 illustrates themarmer in which the 00nsubscribers having their lines connected togethertact mounting plate is locked in its eiective poat a central oiiice todisconnect the linesat the sition; central office without the assistanceof an oper- Fig. 4 shows the contact mounting plate in its 30 ator atthe central oiiice thereby effecting a furunlatched, or ineffective,position; and ther saving in operating time. Fig. 5 illustrates themeans for enabling the These and other objects of the invention arecontact asemblies to be adjustably mounted on attained by means of aplurality of contact asthe contact plate. ,Y semblies mounted in ateletypewriter at various The teletypewriter T, shown in Fig. 1, issimi- 35 predetermined positions. The contacts are lar to theteletypewriter disclosed in Patent adapted to be operated by theteletypewriter 1.745.533 granted February 4, 1930 t0 S- MOFtOn mechanismin response to certain preassigned et al. The disclosure of this Mortonet al. patent teletypewriter signals which may, if desired, be isincorporated herein by reference as a part of l l0 sent from otherteletypewriter stations. In the this Specication. However, the inventionis not 40 preferred embodiment ofthe invention, the oplimited to thistype 'of teletypewriter nor is it eration of the contacts serves tooperate relays limited to the specic structure shown in the whichoperate and lock-up to perform any dedrawings which is a preferredembodiment of the sired functions, such as switching telegraphcirinvention and is shown and described in order to l5 cuits. Also, inthe preferred embodiment of the illustrate and explain the features andPrinciples 45 invention, the operation of a particular contact ofoperation of the invention. unlocks the switching relays and causes themto For purposes of illustration, teletypewriter T is deenergize therebyrestoring the system to its shown to be located at a teletypewritercentral normal condition. If desired, these relays` may office althoughit may be located at an ordinary be designed to perform a variety offunctions, teletypewriter station, if desired. Connected to such asswitching on and off a teletypewriter mothis central oiiice by telegraphlines L1 to Ls, intor at an outlying teletypewriter station. elusive,are the subscribers teletypewriter sta- Most of the contact assembliesare adjustably tions S1 to Ss, inclusive, each of which is p-roattachedto a pivotally mounted plate, located in vided with a teletypewrter Tito T6, inclusive,

si.; the central teletypewriter, and are designed to and ateletypewriter motor M1 to- Ma, inclusive. 55 v ated by an individualpower supply source B1 to Bs, respectively. At stations S1, Sz, S3, andS5 the energizing circuits leading from the respective local powersupply sources to the motors are opened and closed by manually operableswitches A1, A2, A3, and A5, respectively, controlled by the localattendant at each station.

The energizing circuit of the motor M4 is normally open at the armatureand contact A4 of the normally unoperated relay 43. This energizingcircuit is adapted to be opened and closed by any control method thatmay be desired, such as the method described in Patent 1,913,431 grantedJune 13, 1933 to W. Daum. The disclosure of this Daum patent isincorporated herein by reference as a part of this specification. Theenergizing circuit of motor M6 is normally open at contact A5 of relayRe located at the central office. It is to be understood that thesedifferent motor control circuits may be varied as desired to meet theparticular requirements of a given system and that they are shown herefor the purpose of illustrating the wide extent to which the inventionmay be applied. It should also be understood that the invention iscapable of use with any other type of line circuits, such as duplexcircuits.

The teletypewriter T at the central office has a motor M which isoperated by a power supply source B over an energizing circuit closed bya manually operable switch lever A. Motor M operates teletypewriter T bymeans of gears G1 and G2 which alternately raise and lower thereciprocating printing bail I9 to actuate the pull bars selected by thecode bars operated by the selecting mechanism I8, as is described in theMorton et al. patent.

Just above the code bars 80 is a base plate 8l which is attached to theframe 95 of the teletypewriter T by any convenient means, such as screws82. Pivotally mounted on base plate 8| by pivot is a contact plate 83.This pivotal connection provides contact plate 83 with two positions,one an ineffective position and the other an effective position. Contactplate 83 is normally held in its ineffective position by means of aretractile spring 85 asis shown in Fig. 4.

Contact plate 83 is placed in its effective position in response to thereception by relay R of a preassigned teletypewriter code signal. In thepreferred embodiment of the invention this signal is a so-called bellsignal; that is, it is a signal which is designed to effect the ringingof a bell (not shown) in the teletypewriter T. With the type ofteletypewriter shown in Fig. l, a bell signal is what is known as anupper case signal and, accordingly, requires that it be preceded by afigures shift signal. Furthermore, if a code signal corresponding to abell signal should be sent while the platen 21 is in its lower caseposition, the bell pull bar 81 would not be selected but, instead,another pull bar (not shown) would be selected. This other pull bar isnot selected by any upper case signal so its associated type bar (notshown) is blank in the upper case. Y

The reception of a figures code signal by relay R actuates the selectingmechanism. I8 which operates the code bars 8D to select the figures pullbar 41 for enabling its shoulder to be engaged by the printing bail I9.Bail I9 then elevates pull bar '4l and causes the extension 48 toelevate the left end of bell crank'49. This causes: the right end ofbell crank 49 to dip down and 2,112,234 vEach of the motors M1 to Me,inclusive, is operlower catch 19 thereby releasing latch 58. The releaseof latch 55 allows spring 5I to pull the platen assembly 52 forward. Inmoving forward, the platen assembly 52 pulls lever 28 forwardsufliciently to remove slot 'l5 from the path of travel of extension 29of the so-called blank pull bar I4 and, at the same time, closes acontact C7 for a purpose to be explained hereinafter.

Now, when a bell code signal is received by relay R, selectingmechanism. I8 will operate code bars 8D to select the bell pull bar 81.Ball I9 then engages with the shoulder of the bell pull bar 81 andelevates bar 81 with the result that the upper end of bar 8'! pushes theleft end of lever 88 upward. Lever 88 is pivotally mounted at 89 (Fig.4) so that, when its right end goes up, its left end comes down andcarries with it link 90 thereby overcoming the tension of spring 86 bypulling down the right edge of the contact plate 83. This enables latch9| to engage with catch 92 on contact plate 83. Retractile spring 94pulls latch SI to the left for holding contact plate 83 in its effectiveposition.

Contact plate 83 remains in its effective position until a particularpreassigned teletypewriter code signal is received by relay R. In apreferred embodiment of the invention, this particular code signal iswhat is known as the letters shift signal. When this letters shiftsignal is received by relay R, it effects the selection of the letterspull bar 53 by the code bars 88. Bail I9 then elevates the letters pullbar 53 so that the top end of bar 53 hits against lever 93 and causes itto turn counterclockwise around its pivot thereby overcoming the pullexerted by spring 94 and tripping latch 9i. The release of latch 9Iallows retractile spring 83 to pull the contact plate 83 back to itsnormal, or ineffective, position.

Adjustably mounted along the contact plate 83 in the manner shown inFig. 5 are the assemblies for contacts C, C2, C3, C5, and C5. Althoughthese Contact assemblies have been shown to be adjustably mounted, it isto be understood that this is merely one form of the invention and thatthe Contact assemblies may be xedly located by being drilled and tappedonto the contact plate 83. All of these contacts are normally openexcept contact C which is normally closed. Contacts C, C2, C3, C5, andC6 are each designed to be momentarily operated in response to onlyupper case selections of pull bars I7, I2, I3, I5 and I6, respectively,and are then effective to perform their intended functions only whentheir operating signals are preceded by a preassigned code signal which,in the preferred embodiment of the invention, is a so-called bellsignal. Thus, the pull bars II, l2, I3, I5 and I6 may be used forperforming their normal lower and upper case printing functions as wellas for operating contacts C, C2, C3, C5, and C5 to perform variousfunctions, such as switching telegraph lines, as will be describedhereinafter.

In addition to these switching contacts, the switching mechanism alsoincludes the normally open contact C7 which is operated by the platenassembly in the manner described above. The switching mechanism furtherincludes the normally open contacts C1 and C4 which are designed to beoperated by portions of the teletypewriter mechanism only in response tothe reception by the receiving relay R of certain upper caseteletypewriter code signals. The manner of operating contacts C1 and C4will be described hereinafter in connection with the description of theoperation of the system as a whole.

In the operation of the system, let it iirstbe assumed that thesubscriber at station S1 wishes to connect himself through the centralofce to the subscriber at station S3. The subscriber at station S1normally has his switch A1 closed during business hours so that hismotor M1 is energized by his local power supply source B1. Accordingly,the subscriber, by means of his teletypewriter T1, rst transmits afigures shift signal o-ut over line L1, conductor 2li, line L2, throughstation S2, line L2, conductor 2 I, through the normally closed contactsof relay R2, conductor 22, through the normally closed contacts of relayR1, conductor 23, sending contacts 26, conductor I0, receiving relay R,conductor 8, outer left armature of the normally unoperated relay R4,and then to grounded battery 24.

The figures shift signal transmitted over this p-ath energizes thereceiving relay R which operates the selecting mechanism I6 to selectthe gures pull bar 41 which is then elevated by the printing bail I9. Inrising, pull bar 4'! causes its extension 48 to elevate the left end ofbell crank 49. This causes the right end of bell crank 4S to dip downand lower catch I9 thereby releasing latch 50. 'I'he release of latch 50allows spring 5I toI pull the platen assembly 52 forward. As was statedabove, the forward movement of the platen assembly 52 pulls lever 28forward suiiciently to remove slot I5 from the path of travel ofextension 29 of the so-called blank pull bar I4. At the same time, theforward movement of the platen assembly 52 closes contact Cv for apurpose to be explained hereinafter.

The subscriber at station S1 now transmits a preassigned codecombination of significant current variations which, in this preferredembodiment of the invention, is known as a blank signal, Upon beingreceived at the central o-illce, this particular upper case code signalcauses the selecting mechanism i8 to select the blank pull bar I4.Accordingly, the printing bail I9 elevates the blank pull bar I4 withthe result that extension 29 of pull bar I4 engages with the left end oflever 28 and raises it up. This elevates the left end of lever 30 and,consequently, lowers the right end of lever 3i) thereby allowing spring3| to pull down the left end of lever 32. As a result, the right end oflever 32 is raised and allows the spring contact C4 to close. Thisclosing is only momentary because pull bar I4 is soon lowered by bailIS, and spring 'Il then pulls lever 28 back into the position shown inthe drawing.

It should bey noted that contact C4 can only be closed by this uppercase blank signal because, when the platen assembly 52 is in its lowercase position (as is shown in Fig. l), slot 'I5 in lever 28 is thenpositioned over extension 29 of the blank pull bar I4. Elevation of pullbar I4 would then be futile to cause the closing of contact C4 becauseextension 29 would pass through slot I5 and would thus be unable to tiltlever 28.

The closing of contact C4 momentarily closes. the energizing circuit ofrelay R4 from grounded battery 33, through the winding of relay R4,conductor Il, contact C4, conductor 9, conductor 3E, and then to ground3?. As a result, relay R4 becomes energized and operates both itsarmatures. Before contact C4 opens, relay R4 locks-up over a pathleading from grounded battery 33, through the winding of relay R4, innerleft armature, conductor Sti, conductor l, through the normally closedcontact C, conductor 35, conductor 36, and then to ground 3l. At thesame time, the communication circuit is switched from grounded battery24 to the joining conductor 33 and then to conductor 3Q, out over lineLa to station Se, over line Le, conductor 4i?, line L3, and then tostation S3.

Since the subscriber at station Ss normally has his switch A3 closedduring business hours, his motor M3 will be energized at this time byhis local power supply source B3. Accordingly, the system is now incondition for communication to take place between the subscriber atstation S1 and the subscriber at station S3. Signicant currentvariations transmitted by the teletypewriter T1 will travel over lineL1, conductor 2&3, line L2, through station S2, line L2, conducto-r 2l,conductor 22, conductor 23, sending contacts 25, conductor It, receivingrelay R, conductor 8, conductor 38, conductor 39, line Ls, throughstation Se, line Lc, conductor III?, line La, and then to station S3.

When, during the course of communication., the subscriber at station S1wishes to effect a lower case selection, he transmits the so-calledletters shift code signal for causing the selecting mechanism i3 ofteletypewriter T to operate the code bars a@ to select pull bar Uponbeing elevated by the printing bail I9, pull bar 53 elevates itsextension 5ft which correspondingly elevates the left end oi lever 55thereby depressing the right end of lever 55. When the right end oflever 55 is depressed, it causes the left end of bell crank 5t to becorrespondingly depressed, thereby causing the top end of bell crank 51Eto move backward to the rear of the teletypewriter "i". This acts as alever to pull hack the platen assembly 52. In traveling to the rear ofthe teletyp-ewriter T, the platen assembly 52 causes latch 5h to alsomove to the rear of the teletypewriter T with the result that latch 553will engage with the catch i9 in the right end oi bell crank lever 523.This serves to hold the platen assembly 52 in its rearward position andprevents spring 5i from pulling it forward. Thus, the platen assembly 52is latched in its lower case position, as is shown in Fig. l, where itremains until a gures shift signal is received by relay R.

Since both stations S4 and S5 are disconnected from the communicationcircuit at the armatures of relays R1 and R2, respectively, neitherteletypewriter T4 nor teletypewriter T5 will record the signals sentfrom teletypewriter T1 at this time. Teletypewriter Ts will also notrecord these signals due to the fact that the energizing circuit for itsmotor M6 is open at contact Ae of relay Rs. However, with the system inthe condition shown in the drawings, teletypewriter T2 will follow thesignals transmitted by teletypewriter T1 because the energizing circuitfor its motor M2 is closed at switch A2. If the subscriber at station S2nds that the message being transmitted from station S1 to station S3 isof no interest to him, he can open switch A2 thereby shutting clown hismotor M2 with the result that his teletypewriter T2 will not now recordthe signals being transmitted.

Thus, the subscriber at station S1, which may be located at a remotepoint, has connected himself through the central crice to the distantsubscribers station S3 without any assistance from an operator at thecentral office. In other words,

the subscriber at station S1 has switched both his and the othersubscribers lines 8 and 39 from their terminations at batteries 24 and25, respectively, to the joining conductor 38 thereby switching the lineconductors 3 and 39 together. Consequently, a considerable saving inoperating time is effected since the subscriber at station S1 simplytransmits the upper case code combination assigned to select pull bar I4which closes contact C4 to operate relay R4 which immediately switchesthe two lines 8 and 39 together without any act by an operator at thecentral oce. This saving in operating time is of importance in certaintypes of business where time is of the essence and promptness in puttingcalls through is essential.

When the subscribers at stations S1 and S3 have finished communicatingwith each other, either one of them may effect a disconnection of theirlines 8 and 39 at the central oflice by transmitting, from eitherstation S1 or station S3, a figures shift signal followed by apreassigned telegraphic signal, which in this preferred embodiment ofthe invention, is a bell signal. This bell signal is received by thereceiving relay R at the central office which accordingly actuates theselecting mechanism |8 to operate the code bars 83 to select the bellpull bar 81. The resulting elevation of bar 3l by the reciprocating bailI9 causes lever 88 to be tilted thereby pulling down the contact plate83 which is then latched in its effective position by latch 9| as wasdescribed above.

Then, either of the subscribers transmits another preassigned codesignal which causes code b-ars 86 to Select pull bar Bail I9 thenelevates pull bar which momentarily opens the normally closed contact Cthereby opening the locking-up circuit of relay R4. Consequently, relayR4 releases its armatures and switches the line conductors 8 and 39 fromthe joining conductor 38 to batteries 24 and 25, respectively, therebydisconnecting stations S1 and S3 from each other and restoring thecircuits to their normal condition. If desired, the subscriber atstation S2 may also eiect this disconnection. Since this disconnectionis accomplished by any of the connected subscribers without theassistance of an operator at the central ofce, a further saving inoperating time is eiTected.

The nature of the business of the subscriber at station S1 may be suchthat it woul-d be desirable for him to send a message to both thesubscriber at station S3 and the subscriber at station Se (which may,for example, be an outlying station near the central oliice) and havethe message recorded practically simultaneously by the teletypewritersT3 and Ts. To accomplish this conference connection, it is firstnecessary to start the teletypewriter motor Me at station Se byenergizing relay Re. Accordingly, the subscriber at station S1 transmitsa figures shift signal for selecting the figures pull bar 4l to effectthe release o1" latch 53 which then allows the platen assembly 52 to bepulled forward by spring 5|. In moving forward, the platen assembly 52carries latch 58 forward along the top edge of bell crank lever 49thereby forcing down the right end of bell crank lever 9 to closecontact C7. Since latch 50 now engages with the catch 19 in the rightend of bell crank lever 49, contact C7 will remain closed during thetime that the platen assembly 52 remains in its upper case position.

The subscriber at station S1 next transmits a bell signal over line L1,conductor 20, line L2,

through station S2, line L2, conductor 2|, conductor 22, conductor 23,sending contacts 26, conductor l0, receiving relay R, conductor 8, andthen to grounded battery 24. This elects the selection of the bell pullbar 87 which causes the contact plate 83 to be latched in its effectiveposition in the manner described above. The subscriber at station S1 nowtransmits a preassigned combination of code impulses over the circuittraced above. This code combination causes the selecting mechanism 8 ofteletypewriter T to select pull bar |6 which is then operated by theprinting bail I9 to close contact Cs momentarily. A path for energizingrelay Re is now closed from grounded battery 4|, through the winding ofrelay Re, conductor 6, through contact C6, conductor '|6, conductor 9,con-ductor 36, and then to ground 31.

As a result, relay Re operates its armatures and locks-up through a pathfrom battery 4|, through the winding of relay Re, operated leftarmature, conductor 34, conductor through the normally closed contact C,conductor 35, conductor 36, and then to ground 31. At the same time, theright armature of relay Re is operated and closes a path from powersupply source Bs at station Se, over line conductor 45, operatedarmature and contact Ae of relay Re, line conductor 46, motor Ms, andthen back to power supply source Bs thereby energizing motor Me andstarting it into operation. The subscriber at station S1 then transmitsthe code signal for selecting pull bar i4 in the teletypewriter T at thecentral office. When bail I9 elevates pull bar I4, contact C4 will bemomentarily closed and relay R4 will operate its armatures and lockup inthe manner described above.

Messages now sent from station S1 will pass through station S2, throughthe central office, and then through stations Se and S3. 'Ihe messageswill thus be recorded practically simultaneously on both theteletypewriters T3 and Ts. They will also be recorded on theteletypewriter T2 at station S2 provided the subscriber at this stationhas his switch A2 closed. The subscriber at station S3 can transmitmessages to any of the connected stations and these messages will bepractically simultaneously recorded by the teletypewriters T1, T2, andTs. Likewise, the subscriber at station Se can also send messages whichwill be recorded on all of the connected teletypewriters.

At the close of communication, if the platen assembly 52 happens to bein its upper case position, any of the subscribers at stations S1, Sz,S3, or Se may disconnect the conference connection by transmitting abell signal to place plate 83 in its efrective position and by thentransmitting the preassigned code signal for selecting pull bar whichwill momentarily open the normally closed contact C as was describedabove. However, if the platen assembly 52 happens to be in its lowercase position, then the bell signal must be preceded by a gures signalbefore contact plate 83 can be placed in its effective position. Theopening of contact C will open the lockingup circuits of both relays R4and Rs and will cause them to release their armatures. This switches thecommunication circuit from conductors 8 and 39 to grounded batteries 24and as was described above. At the same time, the energizing circuit ofmotor Me is opened at contact As of relay Re and, consequently, motor M6stops running. The circuits are thus restored to their normal condition.

In the event that the subscriber at station S1 wishes to communicatewith the subscriber at station S4 (which may, for example, be anoutlying station near the central cnice), he will transmit the guresshift signal to cause the platen 2l to be shifted to its upper caseposition. The subscriber will then transmit a preassigned upper casecode signal which, upon being received by the receiving relay R, willeffect the selection of pull bar II b-y the selecting mechanism I8 andthe code bars 80. The elevation of pull bar I I by bail I9 will, bymeans of ratchet l and gear 58, drive the top of type bar 59 downward inan arcuate path. The projection 84 on bar 59 will then hit lever 60thereby tilting downward the right end of lever 6I. This drives the topend of lever 6I to the right and allows spring 62 to pull down the rightend oi lever 63 into latching engagement with the top end of lever 6I.Consequently, the left end of lever 63, which is normally locatedimmediately beneath the printing bail I9, as shown in the drawings, isdriven upward to close contact C1 momentarily. It should be noted thatcontact C1 can only be closed by an upper case selection of pull bar I Ibecause, when the platen assembly 52 is in its lower case position,lever 66 is carried to the rear of teletypewriter T a short distancewhich is sufiicient to remove it from the path of travel of projection84.

The closure of contact C1 closes a path from grounded battery 64,through the winding of relay R1, along conductor I, through contact C1,conductor 65, conductor 36, and then to ground 3l. Consequently, relayR1 operates both its armatures and locks-up through its right armatureover a path from grounded battery 64, winding of relay R1, operatedright armature and contact of relay R1, conductor 34, conductor I,normally closed contact C, conductor 35, conductor 36, and then toground 31. It is necessary that relay R1 be designed to lock-up quicklybecause, when the reciprocating bail I9 cornes down, it strikes the leftend of lever 63 thereby knocking the right end of lever 63 up out oflatching engagement with the top end of lever 6l. This permits contactC1 to resume its normally open position.

The operation of the two left armatures o'f relay R1 opens the normallyclosed make-beforebreak left contacts of relay R1 and closes a path fromconductor 22, over the inner left armature of relay R1, conductor 56,line L4, through station S4, back over line L4, conductor 61, outer leftarmature of relay R1, conductor 23, sending contacts 26, conductor Il),relay R, conductor 8, and then to grounded battery 24. The subscriber atstation S1 now transmits motor start signals, such as those described inthe Daum patent mentioned above, which eect the energization of a relay43 at station S4 similar to the motor control relay disclosed in theDaum patent. Upon being energized, motor control relay 43 operates itsarmature to close the contact A4 thereby closing the energizing circuitoi motor M4 and starting motor M4 into operation.

Communication may now take place between stations S1, S2, and S4, thesignals passing out over line L1, conductor 2B, line L2, through stationS2, line L2, conductor 2l, conductor 22, conductor 66, line L4, through`station S4, line L4, conductor 6I, conductor 23, and then to groundedbattery 24 as was described above. These signals will also pass throughthe receiving relay R. It might be mentioned here that this is the casewith all connections between the various subscribers stations; that is,receiving relay R follows all the signals sent between these stationsthereby making a complete record of all the communication which takesplace throughout the system.

At the close oi communication, any of the subscribers at the threeconnected stations S1, Sz, and S4 may, after rst putting the platenassembly 52 into its upper case position in the manner described above,send a bell signal followed by the code signal for selecting pull barI'I which momentarily opens contact C with the consequent opening of thelocking-up circuit of relay R1. Relay R1 now releases its armatures andits make-before-break contacts now open the circuit leading to stationS4 and connect conductor 22 directly to conductor 23. Incidentally, themotor at station S4 may be stopped by any of the subscribers in themanner described in the Daum patent. It might be stated here that, inthis ernbodiment of the invention, they central oice operator can effectany of the connections and disconnections between any oi the subscribersstations because her sending contacts 26 are always connected in serieswith the communication circuits. This circuit construction can be modiedin accordance with the requirements of dierent systems.

If the subscriber at station S1 wishes to send a message to be recordedby the teletypewriters Ta and T4 at stations S3 and S4 (leaving stationS2 out of consideration for the sake of simplicity) he will, after rstcausing contact plate 83 to be put in its effective position in themanner described above, send the code signals to select pull bars II andI4 for closing contacts C1 and C4. This will operate relays R1 and R4which will lock-up as described above to close the lines leading tostations S3 and S4. nected subscribers may disconnect this confer'- enceconnection, after placing contact plate 83 in its effective position, bysending the code signal to select pull bar I'I for opening contact C.This opens the locking-up circuits of both relays R1 and R4 therebyrestoring the system to its normal condition.

Also, if the subscriber at station S1 wishes to send a message to berecorded by the teletypewriters at each of the stations S3, S4, and Se(again leaving station Sz out of consideration for the sake ofsimplication), he will follow the same procedure as that outlined in thepreceding paragraph except that he will, in addition, send the codesignal to select pull bar I6. The operation of pull bar I6 will closecontact Cf; and will operate relay Re which will lock-up and close theenergizing circuit of motor Ms at station Ss thereby conditioningstation Ss for the reception and transmission of messages. Any of theconnected subscribers, or the central oiiice operator, may disconnectthis conference connection in the manner described above.

Likewise, the subscriber at station S1 may connect himself through thecentral oflice to station S5 by first transmitting the gures shiftsignal for shifting platen 2l in teletypewrter T to its upper caseposition. The subscriber at station S1 then transmits a bell signal(thereby placing contact plate 83 in its eiective position) followed bythe preassigned code combination for selecting pull bar I2. Theelevation of pull bar I2 by bail I9 momentarily closes contact C2thereby closing the energizing path for relay R2 from grounded battery68, through the winding of relay R2, con- Any of the conductor 2,contact C2, conductor 99, conductor 9, conductor 36, and then to ground31 thereby energizing relay R2.

Upon being energized relay R2 operates its armatures and locks-ups frombattery 68, through the winding of relay R2, operated left armature,con-ductor 34, conductor 1, through the normally closed contact C,conductor 35, conductor 36, and then to ground 31. In operating its tworight armatures relay R2 switches the line circuit from along conductor2 I, over the outer right operated armature and make-before-breakcontact of relay R2, conductor 69, line L5, teletypewriter T at stationS5, back over line L5, conductor 10, inner operated right armature andmake-before-break contact of relay R2, conductor 22, conductor 23, andthen through the receiving relay R to grounded battery 24.

If a conference connection is desired, other stations may be connectedinto the communication circuit in the manner described above. At theclose of communication, any of the connected subscribers may disconnectthe connection by effecting the operation, or opening, of the normallyclosed Contact C at the central ofce in the manner described above.

In the event that it is desired to connect some other station into thecommunication circuit, or to perform any other switching function, theplaten 21 is first shifted to its upper case position in the mannerdescribed above. After a bell signal has been sent to place the contactplate 83 in its effective position, the preassigned upper case codecombination is transmitted for selecting pull bar I3.

The operation of pull bar I3 by bail I9 momentarily closes the switchingcontact C3 for enabling relay R2 to operate over a path traced fromgrounded battery 1I through the winding y of relay R3, conductor 3,contact C3, conductor armature, conductor 34, conductor 1, through thenormally closed contact C, conductor 35, conductor 39, and then toground 31. In operating its right armatures, relay R3 will perform thedesired switching function.

When it is desired to ldiscontinue the switching operation, the contactplate 83 is placed in its eective position in the manner describedabove, the upper case code signal is sent for causing pull bar I1 toopen the normally closed contact C which opens the locking-up circuit ofrelay R3 thereby causing relay R3 to release its armatures thusrestoring the system to its normal condition.

If it is desired to perform still other switching functions, they may beeffected by rst shifting the platen 21 to its upper case position. Aftersending a bell signal to place contact plate 83 in its effectiveposition, the preassigned upper case code combination for selecting pullbar I 5 is then transmitted. The elevation of pull bar I5 momentarilyoperates the switching contact C5 for closing a path from groundedbattery 13, through the winding of relay R5, conductorY 5, contact C5,conductor 14, conductor 9, conducto-r 36, and then to ground 31 therebyenergizing relay Rs. Upon operating its armatures, relay R5 will lock-upover a path leading from grounded battery 13, through the winding ofrelay R5, operated left armature, conductor 34, conductor 1,

through the normally closed contact C, conductor 35, conductor 36, andthen to ground 31. In operating its right armatures, relay R5 willperform the desired switching functions.

When Iit is desired to terminate this switching operation, the contact'plate 83 is placed in its effective position in the manner describedabove and the upper case signal for effecting the opening of thenormally closed contact C is transmitted thereby opening the locking-upcircuit of relay R5 which now releases its armatures and restores thesystem to its normally unoperated condition.

Another switching function may be accomplished by means of contact C7which is operated by movement of the platen assembly 52 as was describedabove. That is, contact C7 is closed when platen assembly 52 is movedforward to its upper case position and is opened when platen assembly 52moves back to its lower case position. This opening and closing ofcontact C7 opens and closes the path along conductors 42 and 44 and maybe utilized for accomplishing any desired function analogous to thosedescribed above.

If additional operations, or functions, are desired, more contacts canbe mounted upon the contact plate 83 and can be connected into thesystem in a manner similar to that in which the other contacts areconnected.

Whereas the operation of the system has been described principally withreference to connections originating from the dominant station S1, it isto be understood that the connections described above may be effectedand disconnected. in a similar manner by the subscriber at the otherdominant station S2. It is to be further understood that other dominantstations may be added according to the particular requirements of anindividual system.

For the purpose of illustration, contact C1 has been shown to beoperable by an individual arrangement of the teletypewriter apparatus.If it is desired to have levers 69, 8l, and 63 perform some otherfunction, contact C1 may be mounted on the contact plate 83 above a pullbar the same as contacts C2, C3, C5, and Ca.

The same applies to contact C4 which has also been shown to be operableby an individual arrangement of the teletypewriter apparatus. If it isdesired to have levers 28, 30, and 32 perform some other function, thismay readily be accom plished by placing contact C4 on the contact plate83 above a pull bar the same as contacts C2, C3, C5 and C5.

All of the contact assemblies on plate 83 have been shown to beadjustably mounted in order that their positions may be readily variedto meet the requirements of different systems. It is to be understoodthat this has been done for the purpose of illustration and that theymay be fixedly mounted on plate 83 by being drilled and tapped thereto.The preferred method of adjustably mounting the contact assemblies isshown in Fig. 5 in which the contact assembly 95 is shown to be providedwith a spring contact CX and a clamp 91 having a screw 98. To installthis contact assembly 9S, it is slid onto the contact plate 83 in such amanner that the clamp 91 embraces the contact plate 83 as shown in Fig.5. The contact assembly 96 is then slid along the contact plate 83 untilit is over the top of the proper pull bar. The screw 98 is thentightened so that the Contact assembly 96 is held firmly in place on thecontact plate 83.

This position ofthe contact assembly 93 may be changed by rst looseningscrew 98, then sliding assembly 9B along contact plate 83 to its newlocation, and then tightening screw 98. Contact assembly St can also bereadily removed by simply loosening screw 98 and then sliding assembly96 off the contact plate 83. Thus, it can be seen that the use of thisadjustably mounted contact assembly 96 renders the apparatus moreflexible and adaptable to meet different and changing requirements ofthe system.

It may be stated here that, after contact plate 83 has been latched inits effective position and after the desired switching relays have beenoperated and have locked-up, then the desired message, or messages, aresent to the connected stations. As soon as a letters code signal appearsin the message, pull bar 53 will be selected by code bars 80 and will beoperated by the reciprocating bail IS. The elevation of pull bar 53operates lever 93 which trips latch 9|. As was described above, therelease of latch 9i permits spring 86 to pull contact plate 83 into itsineffective position. However, this has no effect on the status of theswitching relays at this time because all the operated switching relaysremain locked-up. This is because the movement of contact plate 83 fromits effective `position to its ineffective position does not open thenormally closed contact C. Contact C remains closed until contact plate83 is again placed in its effective position and pull bar I1 operated aswas described above.

Thus, by means of this invention, the Various pull bars of theteletypewriter T at the central office may be used for performing theirregular printing functions in response to both upper and lower caseselections. The restriction of the switching functions of the pull barsto only those upper case selections which have been preceded by a bellsignal facilitates regular communication between the stations during theperiod that the contact plate 83 is in its ineffective position. This isdue to the fact that, if contact plate 83 were not in its ineffectiveposition, every time the pull bars should be operated they would closetheir contacts to operate the particular switching relays associatedtherewith.

It is to be understood that this specific application of the inventionhas been shown and described for purposes of explaining the principlesand features of operation of the invention. Many changes may be made inthe construction shown without exceeding the scope of the invention.More switching contacts to be operated by the pull bars of theteletypewriter at the central cnice may be added whenever desired toperform any functions that may be required. Likewise, the circuitconnections of the various subscribers stations may be varied as desiredto meet the requirements of any particular communication system.

For example, the teletypewriter at each subscribers station could beprovided with these switching contacts and circuit connections. Thiswould enable a subscriber to perform the various switching operationsdesired without sacrificing the ordinary upper and lower case printingfunctions associated With the pull bars of his teletype- Writer. Thus,after connecting himself to the desired stations, the subscriber couldavail himself completely of the ordinary printing functions of histeletypewriter.

What is claimed is:

l. A teletypewriter having pull bars, selecting mechanism for selectingcertain of the pull bars, a bail for elevating those pull bars selectedby the selecting mechanism, a plate pivotally mountedv near the pullbars, contacts mounted upon the plate and positioned above the pullbars, said contacts being adapted to be operated by the pull bars whenthe pull bars are elevated, said pivoted plate having an ineffectiveposition for elevating the contacts beyond the reach of the pull barsand an effective position for lowering the contacts into the reach ofthe pull bars, biasing means for tilting the pivoted plate into itsineffective position, and control means for tilting the plate into itseffective position.

2. A teletypewriter having a plurality of pull bars, selecting mechanismfor selecting certain of the pull bars, a bail for elevating those pullbars selected by the selecting mechanism, a plate pivotally mounted nearthe pull bars, contacts mounted upon the plate and positionedimmediately above the pull bars, said contacts being adapted to beoperated by the pull bars when the pull bars are elevated, circuitsadapted to be opened and closed by the contacts, said pivoted platehaving an ineffective position for elevating the contacts beyond thereach of the pull bars and an eiective position for lowering thecontacts into the reach of the pull bars, biasing means for tilting thepivoted plate into its ineffective position, control means for tiltingthe plate into its effective position, and locking means for locking theplate in its elective position.

3. A teletypewriter having a plurality of pull bars, selecting mechanismfor selecting certain of the pull bars, a bail for elevating those pullbars selected by the selecting mechanism, a plate pivotally mounted inthe teletypewriter just above the pull bars, and a plurality of contactsadjustably mounted upon the plate in operative relationship with thepull bars, said contacts being adapted to be operated by the pull bars.

4. A teletypewriter having a plurality of pull bars, areciprocating'bail for elevating the pull bars, a base plate locatednear the tops of the pull bars, a contact plate pivotally mounted uponthe base plate, a plurality of contact assemblies mounted upon thecontact plate, each of said con--` tact assemblies having a contactprojecting over the edge of the contact plate and adapted to be operatedby the pull bars when elevated by the bail, said Contact plate having anineffective position for maintaining the contacts above the upper limitof the path of travel of the pull bars and an ellective position forlowering the contacts into the path of travel of the pull bars, and aspring for holding the contact plate in its ineffective position.

5. A teletypewriter having a plurality of pull bars, a reciprocatingbail for elevating the pull bars, a base plate located near the tops ofthe pull bars, a contact plate pivotally mounted upon the base plate, aplurality of contact assemblies mounted upon the contact plate, each ofsaid contact assemblies having a contact projecting over the edge of thecontact plate and adapted to be operated by the pull bars when elevatedby the bail, said contact plate having an ineffective position formaintaining the contacts above the upper limit of the path of travel ofthe pull bars and an effective position for lowering the contacts intothe path of travel of the pull bars, a spring for holding the contactplate in its ineifective position, a latch for latching the contactplate in its effective position, and a lever for bringing the contactplate into latching engagement with the latch.

6. A teletypewriter having a plurality of pull bars, a reciprocatingbail for elevating the pull bars, a base plate located near the tops ofthe pull bars, a Contact plate pivotally mounted upon the base plate, aplurality of contact assemblies mounted upon the contact plate, each ofsaid contact assemblies having a contact projecting over the edge of thecontact plate and adapted to be operated by the pull bars when elevatedby the bail, said contact plate having an ineffective position formaintaining the contacts above the upper limit of the path of travel ofthe pull bars and an eliective position for lowering the contacts intothe path of travel of the pull bars, a spring for holding the contactplate in its ineffective position, a latch for latching the contactplate in its effective position, and a lever for bringing the contactplate into latching engagement with the latch, said lever being adaptedt0 be operated by a preassigned pull bar of the teletypewriter.

7. A teletypewriter having a plurality of pull bars, a reciprocatingbail for elevating the pull bars, a base plate located near the tops ofthe pull bars, a contact plate pivotally mounted upon the base plate, aplurality of contact assemblies mounted upon the contact plate, each ofsaid contact assemblies having a contact projecting over the edge of thecontact plate and adapted to be operated by the pull bars when elevatedby the bail, said contact plate having an ineffective position formaintaining the contacts above the upper limit of the path of travel ofthe pull bars and an effective position for lowering the contacts intothe path of travel of the pull bars, a spring for holding the contactplate in its ineffective position, a latch for latching the contactplate in its eiective position, a rst lever for bringing the contactplate into latching engagement with the latch, and a second lever forreleasing the latch from its latching engagement with the contact plate.

8. A teletypewriter having a plurality of pull bars, a reciprocatingbail for elevating the pull bars, a base plate located near the tops ofthe pull bars, a contact plate pivotally mounted upon the base plate, aplurality of contact assemblies mounted upon the contact plate, each ofsaid contact assemblies having a contact projecting over the edge of thecontact plate and adapted to be operated by the pull bars when elevatedby the bail, said contact plate having an ineffective position formaintaining the contacts above the upper limit of the path of travel ofthe pull bars and an effective position for lowering the contacts intothe path of travel of the pull bars, a spring for holding the contactplate in its ineiective position, a latch for latching the contact platein its eiective position, a rst lever for bringing the contact plateinto latching engagement with the latch, and a second lever forreleasing the latch from its latching engagement with the contact plate,said second lever being adapted to be operated by a preassigned pull barof the teletypewriter.

9. A teletypewriter system having a teletypewriter central oiilce havinga teletypewriter with a platen, a plurality of subscribersteletypewriter stations connected to the central office by a pluralityof telegraph lines, switching apparatus at the central office forenabling a subscriber at one of the teletypewriter stations to establisha con- `ference connection through the central office with a pluralityof the other subscribers stations, said switching apparatus including apivotally mounted contact plate, a plurality of switching contactsmounted upon the contact plate, and control means for operating theswitching contacts in response to the reception by the teletypewriteratthe central office of preassigned teletypewriter signals transmittedover one of the lines by one of the stations.

1G. A teletypewriter system having in combination a teletypewritercentral office having a teletypewriter with a platen, a plurality oftelegraph lines, a plurality of subscribers teletypewriter stationsconnectable to the central office by the telegraph lines and normallydisconnected from each other, and switching apparatus for enabling asubscriber at one of the teletypewriter stations to connect himselfthrough the central oflice to one of the other teletypewriter stations,said switching apparatus including a pivotally mounted contact platemounted in the teletypewriter at the central cnice and a plurality ofswitching contacts mounted upon the contact plate.

1l. A teletypewriter system having in combination a teletypewritercentral ofce having a teletypewriter with a platen having an upper caseposition and a lower case position, shift mechanism for shifting theplaten from one of said positions to the other, a plurality of telegraphlines, a plurality of subscribers` teletypewriter stations connectableto the central oflice by the telegraph lines and normally disconnectedfrom each other,V and switching apparatus for enabling a subscriber atone of the teletypewriter stations to connect himself through thecentral office to one of the other teletypewriter stations, saidswitching apparatus including a pivotally mounted contact plate mountedin the teletypewriter at the central oflice and a plurality of switchingcontacts mounted upon the contact plate, said switching contacts beingoperable only when the platen is shifted to a preassigned case position.

l2. A teletypewriter having pull bars, selecting mechanism for selectingcertain of the pull bars, a reciprocating bail for elevating those pullbars selected by the selecting mechanism, a contact plate pivotallymounted near the pull bars, a plurality of contacts mounted upon thecontact plate and adapted to be operated by the pull bars when the pullbars are elevated, circuits adapted to be opened and closed by thecontacts, and an instrumentality for moving the contact plate about itspivot to render the contacts inoperable.

13. A teletypewriter having shift mechanism, a plurality of pull bars,selecting mechanism for selecting certain of the pull bars, a bail forelevating those pull bars selected by the selecting mechanism, a contactplate pivotally mounted in the teletypewriter near the pull bars, aplurality of contacts mounted upon the contact plate and adapted to beoperated by the pull bars when the pull bars are elevated, a pluralityof circuits adapted to be opened and closed by the operation of thecontacts, said contacts being normally inoperable, and aninstrumentality operable by a preassigned teletypewriter code signal forrendering said contacts operable.

JAMES F. BEATTIE. WALTER R. ROYCROFT.

